Question 1

Definitive identification of Mycoplasma pneumoniae is accomplished by which technique?&#10;A)Hemadsorption of guinea pig erythrocytes&#10;B)Traditional biochemical tests such as indole and oxidase&#10;C)Direct detection methods such as PCR or ELISA&#10;D)All of the above are correct.

Accepted Answer

Because only M. pneumoniae and one serovar of U. urealyticum hemadsorb, definitive identification of M. pneumoniae is accomplished by overlaying suspicious colonies with 0.5% guinea pig erythrocytes in phosphate-buffered saline instead of water. After 20 to 30 minutes at room temperature, colonies are observed for adherence of red blood cells.

Question 2

The natural habitat of Mycoplasma sp., which causes infectious disease in humans, can best be described as&#10;A)the mucous membranes of humans.&#10;B)the aquatic environment.&#10;C)the natural environment.&#10;D)the genitourinary tract of animals.

Accepted Answer

Mycoplasmas are part of the microbial flora of humans and are found mainly in the oropharynx, upper respiratory tract, and genitourinary tract. Besides those that are considered primarily as commensals, considerable evidence indicates the pathogenicity of some mycoplasmas; for others, a role in a particular disease is less clearly delineated.

Question 3

On agar, M. pneumoniae will appear as spherical, grainy, yellowish forms that are embedded in the agar, with a thin outer layer . The agar surface is examined under 40´ magnification every 24 to 72 hours. Because only M. pneumoniae and one serovar of U. urealyticum hemadsorb, definitive identification of M. pneumoniae is accomplished by overlaying suspicious colonies with 0.5% guinea pig erythrocytes in phosphate-buffered saline instead of water. After 20 to 30 minutes at room temperature, colonies are observed for adherence of red blood cells.
Which of the following agents lacks a cell wall and is the smallest known free-living form?

A)Chlamydia
B)Mycoplasma
C)Rickettsia
D)Coxiella

B
Chapter 47 addresses a group of bacteria, the mycoplasmas, which are the smallest known free-living forms. Unlike all other bacteria, these prokaryotes do not have a cell wall.

Accepted Answer

Chapter 47 addresses a group of bacteria, the mycoplasmas, which are the smallest known free-living forms. Unlike all other bacteria, these prokaryotes do not have a cell wall.

Question 4

Definitive identification of which of the following organisms is accomplished by hemadsorption techniques?&#10;A)Chlamydia trachomatis&#10;B)Mycoplasma hominis&#10;C)Mycoplasma pneumoniae&#10;D)Ureaplasma urealyticum

Accepted Answer

Hemadsorption techniques are used to identify Mycoplasma pneumoniae, which can bind to erythrocytes (red blood cells) and cause them to agglutinate (clump together). This can be visualized under a microscope as a hemadsorption effect, allowing for definitive identification of the organism. Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum are not typically identified through hemadsorption techniques.

Question 5

Media that can be used for isolation of Mycoplasma include&#10;A)Thayer-Martin agar with vitamin K.&#10;B)5% sheep blood and IsoVitaleX.&#10;C)beef or soybean protein with serum and fresh yeast extract.&#10;D)Hemin and NAD supplements.

Accepted Answer

In general, the medium for mycoplasma isolation contains a beef or soybean protein with serum, fresh yeast extract, and other factors. Of importance, because these organisms grow more slowly than most other bacteria, the media must be selective to prevent overgrowth of faster-growing organisms that may be present in a clinical sample.

Deck 44: Cell Wall-Deficient Bacteria: Mycoplasma and Ureaplasma